Laying bare ... David talks about his family, the subject of his 'breathtakingly disrespectful celebration

Among the revelations about his late mother Sarah and elderly father Colin is his mum’s long-running affair — and how even on her 75th birthday she sent her lover an email screaming: “My clitoris is on fire!”

Other moments in the act see the former Baddiel And Skinner star revealing how his father made a noise like a “wounded walrus” during sex, while his mother would moan her lover’s name as she pleasured herself.

Disconcertingly for the young Baddiel, his name was David too.

And he even tells how his Holocaust-survivor grandfather loved to visit the brothels of London’s seedy Soho to cavort with prostitutes.

Baddiel himself admits in the programme notes that the act is a “hugely disrespectful celebration” of his family, and confesses that close pals are baffled by his lurid honesty.

His defence is that his mother died two years ago, while his 81-year-old father is now in the grip of dementia — so they cannot be left red-faced by their stories being told.

He also sees it as a “twisted love letter” to them both.

Remarkably, the £22.50-a-head show at south London’s Menier Chocolate Factory venue even seems to come with the apparent approval of his writer brother Ivor, 53, who appears in a pre-recorded video segment.

On Friday night The Sun was in the audience to hear all of 51-year-old David’s eyebrow-raising revelations.

Running through the act is the story of his mother’s adulterous affair with golfing memorabilia salesman David White, which began in the Seventies and continued on and off until her death in 2014.

Baddiel, who has a daughter Dolly, 14, and son Ezra, 11, with partner and fellow comic Morwenna Banks, says on stage: “My mother was not ashamed of her affair with David White. On the contrary, she was proud.

“She felt in a very 1970s way that having an affair was glamorous and so would talk about it all the time.”

In a video segment, brother Ivor reveals how he brought a new girlfriend to meet his mother for the first time, only for her to mention White and explain that he was her “lover of 20 years”.

Laying bare ... David with the Baddiels, the subject of his 'breathtakingly disrespectful celebration'

Husband Colin, a Welsh-born research chemist, never knew of the relationship through “an incredible feat of willed self-ignorance”, despite a string of close calls.

In one instance his mother wrote David White a card with the golf-themed message: “In memory of the Masters when you were my master” — which a young David Baddiel assumed was for him and opened in front of his father, forcing him to bluster that he didn’t understand the odd phrase.

A horrified Baddiel says on stage: “It brings up an image of my mother and David White in black leather plus fours and Pringle gimp masks.”

But on many occasions, along with younger brother Dan, 49, the three boys were left wishing they were as clueless as their father about the double life of their mother, who Baddiel believes used sex to rebel against society’s expectations of her as a seemingly meek Jewish housewife.

Even much later in life and suffering from a series of physical ailments, Sarah continued her relationship.

Baddiel is red-faced as he tells how in 2005 pensioner Sarah wrote her lover an email saying: “The leukaemia and the Crohn’s Disease make me very tired but perhaps you could join me to make the naps more interesting.”

But the email was accidentally also sent to Baddiel and one of his brothers — a gaffe which left David, Ivor and Dan horrified.

More uncomfortable laughs come when Baddiel reads out erotic poetry written by his mother for her lover, found while sorting through her belongings after her death.

One excruciating piece of verse about love-making reads: “I look forward to your coming today when we will be utterly alone to be free to love always/And allow you to nibble my clitoris as you devoured the spare ribs”.

Baddiel himself has frequently discussed his love of pornographic films and magazines as well as making a string of smutty jokes in previous comedy shows — but some of his material clearly brings unease.

Apologising after showing a recorded clip, Baddiel says: “I’m sorry for using the ‘slag’ word, I wouldn’t use that now. Especially not about my dead mum. Even if she clearly was a bit of a slag.”

Shockingly, Baddiel says he is not even sure whether David White is still alive — or whether he is aware that the intimate details of his life are being given such a public airing.

Perhaps, however, the affair was actually better than when Colin and Sarah were passionate together.

Reminiscing about his childhood, Baddiel recalls his parents having sex so loudly his father sounded like a “wounded walrus”.

On one occasion the noises were so appalling a friend who was staying the night feared one of his parents had died — and the young Baddiel had to assure the pal that both were very much alive and well.

Not even his maternal grand- parents — Jewish refugees who fled to London from Nazi Germany — are safe from Baddiel’s acid tongue.

Brotherly love ... David with brother Ivor, who approves the show's outrageous material

The audience see a recorded section in which Sarah says of her father: “When he came to London we used to say, ‘What did you do today?’ And we knew exactly that he’d been going to Soho.

“He’d say he was going to London and don’t ask where he’s gone, but we didn’t ask too many questions. He enjoyed travelling.”

To his London audience, Baddiel explains: “By travelling, she means f***ing prostitutes. Travelling his penis into paid-for . . .”

Mocking his mum’s attitude to her Holocaust-survivor father, he adds: “My dad loved prostitutes! Crazy for whores! Straight out of Dachau and into Berwick Street”.

And talking later about his mother’s decision to have her father’s chair re-covered with a golf-themed print, he jokes that she must have thought, ‘Well, I had to have it re-covered with something — he’d been f***ing prostitutes on it.’

While sex is at the centre of the show, Baddiel also pokes fun at his father, now suffering from a form of dementia called Pick’s Disease, which causes uncontrolled swearing, irritation, mood swings, and extreme impatience as well as memory loss.

He jokes: “When the neurologist told me that, I said, ‘Sorry, does he have a disease, or have you just met him?’”

And although his views are shocking, Baddiel insists they are a form of tribute and that performing the show leaves him close to tears.